U.S. patent number 8,287,541 [Application Number 12/482,406] was granted by the patent office on 2012-10-16 for fracture fixation device, tools and methods.
This patent grant is currently assigned to Sonoma Orthopedic Products, Inc.. Invention is credited to Nathan Brown, Stephen B. Gunther, Kai U. Mazur, Stephen R. McDaniel, Charles L. Nelson, Trung Ho Pham, Heber Saravia.
United States Patent |
8,287,541 |
Nelson , et al. |
October 16, 2012 |
**Please see images for:
( Certificate of Correction ) ** |
Fracture fixation device, tools and methods
Abstract
A bone fixation device is provided with an elongate body having
a longitudinal axis and having a first state in which at least a
portion of the body is flexible and a second state in which the
body is generally rigid, an actuatable gripper disposed at a distal
location on the elongated body, a hub located on a proximal end of
the elongated body, and an actuator operably connected to the
gripper to deploy the gripper from a retracted configuration to an
expanded configuration. Methods of repairing a fracture of a bone
are also disclosed. One such method comprises inserting a bone
fixation device into an intramedullary space of the bone to place
at least a portion of an elongate body of the fixation device in a
flexible state on one side of the fracture and at least a portion
of a hub on another side of the fracture, and operating an actuator
to deploy at least one gripper of the fixation device to engage an
inner surface of the intramedullary space to anchor the fixation
device to the bone. Various configurations are disclosed for
allowing a device body to change shape as it moves from a flexible
state to a rigid state.
Inventors: |
Nelson; Charles L. (Santa Rosa,
CA), Saravia; Heber (Santa Rosa, CA), McDaniel; Stephen
R. (San Rafael, CA), Pham; Trung Ho (Santa Rosa, CA),
Mazur; Kai U. (Santa Rosa, CA), Gunther; Stephen B.
(Cloverdale, CA), Brown; Nathan (Santa Rosa, CA) |
Assignee: |
Sonoma Orthopedic Products,
Inc. (Santa Rosa, CA)
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Family
ID: |
41417110 |
Appl.
No.: |
12/482,406 |
Filed: |
June 10, 2009 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20100023010 A1 |
Jan 28, 2010 |
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Related U.S. Patent Documents
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Application
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Filing Date |
Patent Number |
Issue Date |
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11383269 |
May 15, 2006 |
7846162 |
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12482406 |
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11383800 |
May 17, 2006 |
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11944366 |
Nov 21, 2007 |
7909825 |
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60682652 |
May 18, 2005 |
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60867011 |
Nov 22, 2006 |
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60866976 |
Nov 22, 2006 |
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60949071 |
Jul 11, 2007 |
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61060440 |
Jun 10, 2008 |
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61060445 |
Jun 10, 2008 |
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61060450 |
Jun 10, 2008 |
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61100635 |
Sep 26, 2008 |
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61100652 |
Sep 26, 2008 |
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61122563 |
Dec 15, 2008 |
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61138920 |
Dec 18, 2008 |
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61117901 |
Nov 25, 2008 |
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Current U.S.
Class: |
606/63;
606/62 |
Current CPC
Class: |
A61B
17/1717 (20130101); A61B 17/7266 (20130101); A61B
17/8872 (20130101); A61B 17/7291 (20130101); A61B
17/7225 (20130101); A61B 17/7208 (20130101); A61B
2017/00004 (20130101); A61B 17/7241 (20130101); A61B
17/1739 (20130101); A61B 2090/062 (20160201); A61B
2090/08021 (20160201) |
Current International
Class: |
A61B
17/58 (20060101) |
Field of
Search: |
;606/62-68 ;138/119
;600/139-152 ;411/21 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2561552 |
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Nov 2005 |
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CA |
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1582163 |
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Nov 2003 |
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EP |
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1815813 |
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Aug 2007 |
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EP |
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WO 97/18769 |
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May 1997 |
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WO |
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WO 98/27876 |
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Jul 1998 |
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WO |
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WO 98/56301 |
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Dec 1998 |
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WO |
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WO 99/20195 |
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Apr 1999 |
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WO |
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WO 00/28906 |
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May 2000 |
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WO |
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WO 01/28443 |
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Apr 2001 |
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WO |
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WO 02/00270 |
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Jan 2002 |
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WO |
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WO 02/00275 |
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Jan 2002 |
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WO |
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WO 02/02158 |
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Jan 2002 |
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WO |
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WO 2005/112804 |
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Dec 2005 |
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WO |
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WO 2006/053210 |
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May 2006 |
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WO |
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WO 2006/124764 |
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Nov 2006 |
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WO |
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Other References
US 6,030,385, 02/2000, Faccioli et al. (withdrawn) cited by other
.
Nelson et al.; U.S. Appl. No. 12/482,388 entitled "Fracture
fixation device, tools and methods," filed Jun. 10, 2009. cited by
other .
Nelson et al.; U.S. Appl. No. 12/482,395 entitled "Fracture
fixation device, tools and methods," filed Jun. 10, 2009. cited by
other .
The Titanium Flexible Humeral Nail System (Quick reference for
surgical technique), Synthes, 1999. cited by other .
The Titanium Flexible Humeral Nail System (Technique Guide),
Synthes, 1999. cited by other .
Andermahr et al., "Anatomy of the clavicle and the intramedullary
nailing of midclavicular fractures," Clinical Anatomy; vol. 20; pp.
48-56; 2007. cited by other.
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Primary Examiner: Merene; Jan Christopher
Attorney, Agent or Firm: Knobbe Martens Olson & Bear,
LLP
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a Continuation-in-Part of U.S. application Ser.
No. 11/383,269, titled "MINIMALLY INVASIVE ACTUABLE BONE FIXATION
DEVICES", filed May 15, 2006 now U.S. Pat. No. 7,846,162 which
claims priority to U.S. Provisional Application No. 60/682,652,
titled "METHOD AND SYSTEM FOR PROVIDING REINFORCEMENT OF BONES",
filed May 18, 2005. This application is also a Continuation-in-part
of U.S. application Ser. No. 11/383,800 filed May 17, 2006 now
abandoned titled "DEPLOYABLE INTRAMEDULLARY STENT SYSTEM FOR
REINFORCEMENT OF BONE" which claims priority to U.S. Provisional
Application No. 60/682,652, titled "METHOD AND SYSTEM FOR PROVIDING
REINFORCEMENT OF BONES", filed May 18, 2005. This application is
also a Continuation-in-Part of U.S. application Ser. No.
11/944,366, titled "FRACTURE FIXATION DEVICE, TOOLS AND METHODS",
filed Nov. 21, 2007 now U.S. Pat. No. 7,909,825 which claims
priority to U.S. provisional applications: No. 60/867,011, titled
"BONE REPAIR IMPLANT WITH CENTRAL RATCHETING GUIDEWIRE", filed Nov.
22, 2006; No. 60/866,976, titled "SURGICAL TOOLS FOR USE IN
DEPLOYING BONE REPAIR DEVICES," filed Nov. 22, 2006; and No.
60/949,071, titled "FRACTURE FIXATION DEVICE, TOOLS AND METHODS",
filed Jul. 11, 2007.
This application claims priority of U.S. Provisional Application
No. 61/060,440, titled "FRACTURE FIXATION DEVICE, TOOLS AND
METHODS" filed Jun. 10, 2008; U.S. Provisional Application No.
61/060,445, titled "FRACTURE FIXATION DEVICE, TOOLS AND METHODS"
filed Jun. 10, 2008; U.S. Provisional Application No. 61/060,450,
titled "FRACTURE FIXATION DEVICE, TOOLS AND METHODS" filed Jun. 10,
2008; U.S. Provisional Application No. 61/100,635, titled "FRACTURE
FIXATION DEVICE, TOOLS AND METHODS" filed Sep. 26, 2008; U.S.
Provisional Application No. 61/100,652, titled "FRACTURE FIXATION
DEVICE, TOOLS AND METHODS" filed Sep. 26, 2008; U.S. Provisional
Application No. 61/122,563, titled "BONE FIXATION DEVICE, TOOLS AND
METHODS" filed Dec. 15, 2008; U.S. Provisional Application No.
61/138,920, titled "BONE FIXATION DEVICE, TOOLS AND METHODS" filed
Dec. 18, 2008; and U.S. Provisional Application No. 61/117,901,
titled "BONE FRACTURE FIXATION SCREWS, SYSTEMS AND METHODS OF USE"
filed Nov. 25, 2008.
Claims
The invention claimed is:
1. A bone fixation device comprising: a generally tubular body
having a circumferential surface, an inner lumen, and a wall
extending therebetween, the body being sized to fit within an
intramedullary space within a bone, the body having a longitudinal
axis; at least one radially expandable gripper disposed within the
body for engaging a surface of the intramedullary space; an
actuator comprising a distal actuator head, the distal actuator
head comprising a ramped surface slideably disposed on an interior
of the at least one radially expandable gripper, the actuator
configured to outwardly actuate the at least one radially
expandable gripper away from the longitudinal axis and away from
the body; a slit through the body wall extending through at least
one complete revolution around the circumferential surface and
axially along at least a portion of the body; and a compression
mechanism configured to apply an axial compression to the body to
move the slit towards a closed position, thereby transforming the
body from a generally flexible state to a generally rigid
state.
2. The bone fixation device of claim 1 further comprising at least
one pair of mating features formed by the slit, wherein one of the
mating features is located on one side of the slit and the other
mating feature is located on the opposite side of the slit.
3. The bone fixation device of claim 2 further comprising at least
two pairs of mating features located within one revolution of the
slit.
4. The bone fixation device of claim 2 further comprising at least
five pairs of mating features located within one revolution of the
slit.
5. The bone fixation device of claim 2 wherein the slit comprises a
sinusoidal pattern that forms the pairs of mating features.
6. The bone fixation device of claim 2 wherein the mating features
of at least one of the pairs interlock to limit axial expansion and
contraction of the body, and to limit axial rotation in both
directions of one part of the body relative to another.
7. The bone fixation device of claim 6 wherein the mating features
comprise L-shaped protuberances extending from each side of the
slit into mating L-shaped cavities in the opposite side of the
slit.
8. The bone fixation device of claim 7 wherein the L-shaped
protuberances on opposite sides of the slit directly interlock with
each other.
9. The bone fixation device of claim 6 wherein the mating features
comprise T-shaped protuberances extending from each side of the
slit into mating T-shaped cavities in the opposite side of the
slit.
10. The bone fixation device of claim 9 wherein the T-shaped
protuberances on opposite sides of the slit directly interlock with
each other.
11. The bone fixation device of claim 6 further comprising at least
three pairs of interlocking features located within one revolution
of the slit.
12. The bone fixation device of claim 6 further comprising at least
seven pairs of interlocking features located within one revolution
of the slit.
13. The bone fixation device of claim 1 wherein the slit comprises
at least three revolutions.
14. The bone fixation device of claim 1 wherein the slit has a
width that varies as it extends around the circumferential surface
such that one portion of the body may axially compress more than
another portion when the slit moves toward the closed position.
15. The bone fixation device of claim 1 further comprising at least
two interdigitated slits extending along at least a portion of the
body.
16. The bone fixation device of claim 1 wherein the compression
mechanism is reversible, such that the axial compression can be
removed thereby transforming the body from a generally rigid state
to a generally flexible state.
17. The bone fixation device of claim 1 comprising at least four
radially expandable grippers coupled to the body for engaging a
surface of the intramedullary space.
18. The bone fixation device of claim 1 further comprising at least
one screw hole extending radially at least partially through the
body for receiving a bone screw to assist in securing the body
within the intramedullary space.
19. A bone fixation device comprising: a generally tubular body
having a circumferential surface, an inner lumen, and a wall
extending therebetween, the body being sized to fit within an
intramedullary space within a bone, the body having a longitudinal
axis; at least one radially expandable gripper disposed within the
body for engaging a surface of the intramedullary space; an
actuator comprising a distal actuator head, the distal actuator
head comprising a ramped surface slideably disposed on an interior
of the at least one radially expandable gripper, the actuator
configured to outwardly actuate the at least one radially
expandable gripper away from the longitudinal axis and away from
the body; a slit through the body wall extending around the
circumferential surface and axially along at least a portion of the
body, wherein the slit comprises at least one revolution; at least
one pair of mating features formed by the slit and located within
one revolution of the slit, wherein the mating features of each of
the at least three one pair interlock to limit axial expansion and
contraction of the body, and to limit axial rotation in both
directions of one part of the body relative to another; and a
compression mechanism configured to apply an axial compression to
the body to move the slit towards a closed position, thereby
transforming the body from a generally flexible state to a
generally rigid state, the compression mechanism being reversible
such that the axial compression can be removed, thereby
transforming the body from a generally rigid state to a generally
flexible state, and wherein the slit has a width that varies as it
extends around the circumferential surface such that one portion of
the body may axially compress more than another portion when the
slit moves toward the closed position, thereby forming a curve in
at least a portion of the body.
20. The bone fixation device of claim 19 further comprising at
least one radially expandable gripper coupled to the body for
engaging a surface of the intramedullary space.
21. A method of repairing a bone fracture comprising: providing an
elongate fixation device having a longitudinal axis and at least a
portion transformable between a generally flexible state and a
generally rigid state, the transformable portion having a slit
extending around at least one complete revolution around its
circumference; inserting the device in the generally flexible state
into an intramedullary canal of the bone across the fracture;
actuating a compression mechanism on the device to move the slit
towards a closed position, thereby transforming the device portion
from the generally flexible state to the generally rigid state;
extending a radially expandable gripper disposed within the
elongated fixation device away from the longitudinal axis by moving
an actuator along the longitudinal axis, the actuator comprising a
distal actuator head with a ramped surface slideably disposed on an
interior of the radially expandable gripper; and engaging the
radially expandable gripper to a surface of the intramedullary
canal.
22. The method of claim 21 wherein the actuating step causes the
portion transformable between the generally flexible state and the
generally rigid state to change from a first shape to a second
shape, the second shape enabling the device to grip at least one
bone surface within the intramedullary space.
23. The method of claim 22 wherein the second shape is similar but
not identical to a shape of the intramedullary space.
24. The method of claim 22 wherein the first shape is generally
straight and the second shape is curved.
25. The method of claim 21 further comprising actuating a radially
expanding gripper after the inserting step.
26. The method of claim 25 wherein the actuation of the compression
mechanism and the actuation of the gripper are accomplished in a
single step.
27. The method of claim 21 further comprising reversing the
compression mechanism to transform the device portion from the
generally rigid state to the generally flexible state, and removing
the device from the bone.
28. The method of claim 21 wherein the transformable portion of the
device comprises a plurality of pairs of mating features formed by
the slit.
29. The method of claim 28 wherein the mating features of at least
one of the pairs interlock to limit axial expansion and contraction
of the transformable portion, and to limit axial rotation in both
directions of one part of the transformable portion relative to
another.
Description
INCORPORATION BY REFERENCE
All publications and patent applications mentioned in this
specification are herein incorporated by reference to the same
extent as if each individual publication or patent application was
specifically and individually indicated to be incorporated by
reference
BACKGROUND OF THE INVENTION
The present invention relates to devices, tools and methods for
providing reinforcement of bones. More specifically, the present
invention relates to devices, tools and methods for providing
reconstruction and reinforcement of bones, including diseased,
osteoporotic and fractured bones. The number and diversity sports
and work related fractures are being driven by several sociological
factors. The diversity of high energy sports has increased and the
participation in these sports has followed the general trend of
affluence and the resultant amount of time for leisure. High energy
sports include skiing, motorcycle riding, snow mobile riding,
snowboarding, mountain biking, road biking, kayaking, and all
terrain vehicle (ATV) riding. As the general affluence of the
economically developed countries has increased the amount and age
of people participating in these activities has increased. Lastly,
the acceptance and ubiquitous application of passive restraint
systems, airbags, in automobiles has created greater numbers of
non-life threatening fractures. In the past, a person that might
expire from a serious automobile accident, now survives with
multiple traumas and resultant fractures.
Bone fractures are a common medical condition both in the young and
old segments of the population. However, with an increasingly aging
population, osteoporosis has become more of a significant medical
concern in part due to the risk of osteoporotic fractures.
Osteoporosis and osteoarthritis are among the most common
conditions to affect the musculoskeletal system, as well as
frequent causes of locomotor pain and disability. Osteoporosis can
occur in both human and animal subjects (e.g. horses). Osteoporosis
(OP) and osteoarthritis (OA) occur in a substantial portion of the
human population over the age of fifty. The National Osteoporosis
Foundation estimates that as many as 44 million Americans are
affected by osteoporosis and low bone mass, leading to fractures in
more than 300,000 people over the age of 65. In 1997 the estimated
cost for osteoporosis related fractures was $13 billion. That
figure increased to $17 billion in 2002 and is projected to
increase to $210-240 billion by 2040. Currently it is expected that
one in two women, and one in four men, over the age of 50 will
suffer an osteoporosis-related fracture. Osteoporosis is the most
important underlying cause of fracture in the elderly. Also, sports
and work-related accidents account for a significant number of bone
fractures seen in emergency rooms among all age groups.
One current treatment of bone fractures includes surgically
resetting the fractured bone. After the surgical procedure, the
fractured area of the body (i.e., where the fractured bone is
located) is often placed in an external cast for an extended period
of time to ensure that the fractured bone heals properly. This can
take several months for the bone to heal and for the patient to
remove the cast before resuming normal activities.
In some instances, an intramedullary (IM) rod or nail is used to
align and stabilize the fracture. In that instance, a metal rod is
placed inside a canal of a bone and fixed in place, typically at
both ends. See, for example, Fixion.RTM. IM(Nail),
www.disc-o-tech.com. Placement of conventional IM rods are
typically a "line of sight" and require access collinear with the
center line of the IM canal. Invariably, this line of sight access
violates, disrupts, and causes damage to important soft tissue
structures such as ligaments, tendons, cartilage, facia, and
epidermis This approach requires incision, access to the canal, and
placement of the IM nail. The nail can be subsequently removed or
left in place. A conventional IM nail procedure requires a similar,
but possibly larger, opening to the space, a long metallic nail
being placed across the fracture, and either subsequent removal,
and or when the nail is not removed, a long term implant of the IM
nail. The outer diameter of the IM nail must be selected for the
minimum inside diameter of the space. Therefore, portions of the IM
nail may not be in contact with the canal. Further, micro-motion
between the bone and the IM nail may cause pain or necrosis of the
bone. In still other cases, infection can occur. The IM nail may be
removed after the fracture has healed. This requires a subsequent
surgery with all of the complications and risks of a later
intrusive procedure. In general, rigid IM rods or nails are
difficult to insert, can damage the bone and require additional
incisions for cross-screws to attach the rods or nails to the
bone.
Some IM nails are inflatable. See, for example, Meta-Fix IM Nailing
System, www.disc-o-tech.com. Such IM nails require inflating the
rod with very high pressures, endangering the surrounding bone.
Inflatable nails have many of the same drawbacks as the rigid IM
nails described above.
External fixation is another technique employed to repair
fractures. In this approach, a rod may traverse the fracture site
outside of the epidermis. The rod is attached to the bone with
trans-dermal screws. If external fixation is used, the patient will
have multiple incisions, screws, and trans-dermal infection paths.
Furthermore, the external fixation is cosmetically intrusive,
bulky, and prone to painful inadvertent manipulation by
environmental conditions such as, for example, bumping into objects
and laying on the device.
Other concepts relating to bone repair are disclosed in, for
example, U.S. Pat. Nos. 5,108,404 to Scholten for Surgical Protocol
for Fixation of Bone Using Inflatable Device; 4,453,539 to
Raftopoulos et al. for Expandable Intramedullary Nail for the
Fixation of Bone Fractures; 4,854,312 to Raftopolous for Expanding
Nail; 4,932,969 to Frey et al. for Joint Endoprosthesis; 5,571,189
to Kuslich for Expandable Fabric Implant for Stabilizing the Spinal
Motion Segment; 4,522,200 to Stednitz for Adjustable Rod; 4,204,531
to Aginsky for Nail with Expanding Mechanism; 5,480,400 to Berger
for Method and Device for Internal Fixation of Bone Fractures;
5,102,413 to Poddar for Inflatable Bone Fixation Device; 5,303,718
to Krajicek for Method and Device for the Osteosynthesis of Bones;
6,358,283 to Hogfors et al. for Implantable Device for Lengthening
and Correcting Malpositions of Skeletal Bones; 6,127,597 to Beyar
et al. for Systems for Percutaneous Bone and Spinal Stabilization,
Fixation and Repair; 6,527,775 to Warburton for Interlocking
Fixation Device for the Distal Radius; U.S. Patent Publication
US2006/0084998 A1 to Levy et al. for Expandable Orthopedic Device;
and PCT Publication WO 2005/112804 A1 to Myers Surgical Solutions,
LLC et. al. for Fracture Fixation and Site Stabilization System.
Other fracture fixation devices, and tools for deploying fracture
fixation devices, have been described in: US Patent Appl. Publ. No.
2006/0254950; U.S. Ser. No. 60/867,011 (filed Nov. 22, 2006); U.S.
Ser. No. 60/866,976 (filed Nov. 22, 2006); and U.S. Ser. No.
60/866,920 (filed Nov. 22, 2006).
In view of the foregoing, it would be desirable to have a device,
system and method for providing effective and minimally invasive
bone reinforcement and fracture fixation to treat fractured or
diseased bones, while improving the ease of insertion, eliminating
cross-screw incisions and minimizing trauma.
SUMMARY OF THE INVENTION
Aspects of the invention relate to embodiments of a bone fixation
device and to methods for using such a device for repairing a bone
fracture. The bone fixation device may include an elongate body
with a longitudinal axis and having a flexible state and a rigid
state. The device further may include a plurality of grippers
disposed at longitudinally-spaced locations along the elongated
body, a rigid hub connected to the elongated body, and an actuator
that is operably-connected to the grippers to deploy the grippers
from a first shape to an expanded second shape. The elongate body
and the rigid hub may or may not be collinear or parallel.
In one embodiment, a bone fixation device is provided with an
elongate body having a longitudinal axis and having a first state
in which at least a portion of the body is flexible and a second
state in which the body is generally rigid, an actuatable gripper
disposed at a distal location on the elongated body, a hub located
on a proximal end of the elongated body, and an actuator operably
connected to the gripper to deploy the gripper from a retracted
configuration to an expanded configuration.
Methods of repairing a fracture of a bone are also disclosed. One
such method comprises inserting a bone fixation device into an
intramedullary space of the bone to place at least a portion of an
elongate body of the fixation device in a flexible state on one
side of the fracture and at least a portion of a hub on another
side of the fracture, and operating an actuator to deploy at least
one gripper of the fixation device to engage an inner surface of
the intramedullary space to anchor the fixation device to the
bone.
According to aspects of the present disclosure, similar methods
involve repairing a fracture of a metatarsal, metacarpal, sternum,
tibia, rib, midshaft radius, ulna, olecranon (elbow), huberus, or
distal fibula. Each of these bones have a distal and proximal
segment, farthest and closest to the heart, respectively, and on
opposite ends of a fracture. The method comprises creating an
intramedullary channel, such that the channel traverses the
fracture of the bone and comprises at least one segment that
substantially follows a curved anatomical contour of the bone; and
inserting a bone fixation device into the intramedullary channel
and across the fracture of the bone, such that at least a portion
of an elongate body of the fixation device in a flexible state is
placed within the curved segment of the channel.
One embodiment of the present invention provides a low weight to
volume mechanical support for fixation, reinforcement and
reconstruction of bone or other regions of the musculo-skeletal
system in both humans and animals. The method of delivery of the
device is another aspect of the invention. The method of delivery
of the device in accordance with the various embodiments of the
invention reduces the trauma created during surgery, decreasing the
risks associated with infection and thereby decreasing the
recuperation time of the patient. The framework may in one
embodiment include an expandable and contractible structure to
permit re-placement and removal of the reinforcement structure or
framework.
In accordance with the various embodiments of the present
invention, the mechanical supporting framework or device may be
made from a variety of materials such as metal, composite, plastic
or amorphous materials, which include, but are not limited to,
steel, stainless steel, cobalt chromium plated steel, titanium,
nickel titanium alloy (nitinol), super-elastic alloy, and
polymethylmethacrylate (PMMA). The device may also include other
polymeric materials that are biocompatible and provide mechanical
strength, that include polymeric material with ability to carry and
delivery therapeutic agents, that include bioabsorbable properties,
as well as composite materials and composite materials of titanium
and polyetheretherketone (PEEK.TM.), composite materials of
polymers and minerals, composite materials of polymers and glass
fibers, composite materials of metal, polymer, and minerals.
Within the scope of the present invention, each of the
aforementioned types of device may further be coated with proteins
from synthetic or animal source, or include collagen coated
structures, and radioactive or brachytherapy materials.
Furthermore, the construction of the supporting framework or device
may include radio-opaque markers or components that assist in their
location during and after placement in the bone or other region of
the musculo-skeletal systems.
Further, the reinforcement device may, in one embodiment, be osteo
incorporating, such that the reinforcement device may be integrated
into the bone.
In still another embodiment of the invention, a method of repairing
a bone fracture is disclosed that comprises: accessing a fracture
along a length of a bone through a bony protuberance at an access
point at an end of a bone; advancing a bone fixation device into a
space through the access point at the end of the bone; bending a
portion of the bone fixation device along its length to traverse
the fracture; and locking the bone fixation device into place
within the space of the bone. The method can also include the step
of advancing an obturator through the bony protuberance and across
the fracture prior to advancing the bone fixation device into the
space. In yet another embodiment of the method, the step of
anchoring the bone fixation device within the space can be
included. In another embodiment of the invention, a method of
repairing bone is disclosed whereby the area of the affected bone
is remediated by advancing the device through an opening in the
middle of the bone, below the metaphysis or at a point away from a
joint or bony protuberance.
An aspect of the invention discloses a removable bone fixation
device that uses a single port of insertion and has a single-end of
remote actuation wherein a bone fixation device stabilizes bone
after it has traversed the fracture. The bone fixation device is
adapted to provide a single end in one area or location where the
device initiates interaction with bone. The device can be deployed
such that the device interacts with bone. Single portal insertion
and single-end remote actuation enables the surgeon to insert and
deploy the device, deactivate and remove the device, reduce bone
fractures, displace or compress the bone, and lock the device in
place. In addition, the single-end actuation enables the device to
grip bone, compresses the rigidizable flexible body, permits axial,
torsional and angular adjustments to its position during surgery,
and releases the device from the bone during its removal procedure.
A removable extractor can be provided in some embodiments of the
device to enable the device to be placed and extracted by
deployment and remote actuation from a single end. The device of
the invention can be adapted and configured to provide at least one
rigidizable flexible body or sleeve. Further the body can be
configured to be flexible in all angles and directions. The
flexibility provided is in selective planes and angles in the
Cartesian, polar, or cylindrical coordinate systems. Further, in
some embodiments, the body is configured to have a remote actuation
at a single end. Additionally, the body can be configured to have
apertures, windings, etc. The device may be configured to function
with non-flexible bodies for use in bones that have a substantially
straight segment or curved segments with a constant radius of
curvature. Another aspect of the invention includes a bone fixation
device in that has mechanical geometry that interacts with bone by
a change in the size of at least one dimension of a Cartesian,
polar, or spherical coordinate system. Further, in some
embodiments, bioabsorbable materials can be used in conjunction
with the devices, for example by providing specific subcomponents
of the device configured from bioabsorbable materials. A sleeve can
be provided in some embodiments where the sleeve is removable, has
deployment, remote actuation, and a single end. Where a sleeve is
employed, the sleeve can be adapted to provide a deployable
interdigitation process or to provide an aperture along its length
through which the deployable interdigitation process is adapted to
engage bone. In some embodiments, the deployable interdigitation
process is further adapted to engage bone when actuated by the
sleeve. In some embodiments, the bone fixation device further
comprises a cantilever adapted to retain the deployable bone
fixation device within the space. The sleeve can further be adapted
to be expanded and collapsed within the space by a user. One end of
the device can be configured to provide a blunt obturator surface
adapted to advance into the bone. A guiding tip may also be
provided that facilitates guiding the device through the bone. The
device may be hollow and accept a guide wire. The guiding tip may
facilitate placement of the device thereby providing a means to
remove bone in its path (a helical end, a cutting end, or ablative
end). The guiding tip may allow capture, interaction, or insertion
into or around a tube on its internal or external surface. Further,
the deployable bone fixation device can be adapted to receive
external stimulation to provide therapy to the bone. The device can
further be adapted to provide an integral stimulator which provides
therapy to the bone. In still other embodiments, the device can be
adapted to receive deliver therapeutic stimulation to the bone.
The devices disclosed herein may be employed in various regions of
the body, including: spinal, cranial, thoracic, lower extremities
and upper extremities. Additionally, the devices are suitable for a
variety of breaks including, metaphyseal, diaphyseal cortical bone,
cancellous bone, and soft tissue such as ligament attachment and
cartilage attachment . . . .
The fracture fixation devices of various embodiments of the
invention are adapted to be inserted through an opening of a
fractured bone, such as the radius (e.g., through a bony
protuberance on a distal or proximal end or through the midshaft)
into an intramedullary canal of the bone. The device can be
inserted in one embodiment in a line of sight manner collinear or
nearly collinear, or parallel to the central axis of the
intramedullary canal. In another embodiment the device can be
inserted at an angle, radius, or tangency to the axis of the
intramedullary canal. In another embodiment, the device can be
inserted in a manner irrespective of the central axis of the
intramedullary canal. In some embodiments, the fixation device has
two main components, one configured component for being disposed on
the side of the fracture closest to the opening and one component
configured for being disposed on the other side of the fracture
from the opening so that the fixation device traverses the
fracture.
The device components cooperate to align, fix and/or reduce the
fracture so as to promote healing. The device may be removed from
the bone after insertion (e.g., after the fracture has healed or
for other reasons), or it may be left in the bone for an extended
period of time or permanently.
In some embodiments, the fracture fixation device has one or more
actuatable bone engaging mechanisms such as anchors or grippers on
its proximal and/or distal ends. These bone engaging mechanisms may
be used to hold the fixation device to the bone while the bone
heals. In another embodiment, the fracture fixation device has a
plurality of gripper or anchors along its length. In another
embodiment, the fracture fixation device has grippers or anchoring
devices that interdigitate into the bone at an angle greater than
zero degrees and less than 180 degrees to secure the bone segments
of the fracture. In another embodiment the fracture fixation device
has grippers or anchoring features that when activated from a state
that facilitates insertion to a state that captures, aligns, and
fixes the fracture, deploy in a geometry so that the resultant
fixed bone is analogous, nearly identical, or identical to the
geometry of the bone prior to the fracture. In one embodiment of
the device, the flexible body allows insertion through tortuous
paths within bone or created within bone. Upon activation from the
state of insertion to the state of fixation, this device deforms so
as to grip the bone upon multiple surfaces of the now collapsed,
rigid, flexible body. In this collapsed state the device may be
deform in such a way to re-achieve anatomical alignment of the
bone. The device as described above can be fabricated so that it
can have any cross sectional shape.
In some embodiments, to aid in insertion of the device into the
intramedullary canal, the main component of the fracture fixation
device has a substantially flexible state. Thereby, the device,
prior to activation, may not have a rigid section. Once in place,
deployment of the device also causes the components to change from
the flexible state to a rigid state to aid in proper fixation of
the fracture. At least one of the components may be semi-flexible.
Placement of the device may be aided by a detachable rigid member
such as a guide or outrigger. Placement of the device may be aided
by removable rigid member such as a tube or guide wire. At least
one component may provide a bone screw attachment site for the
fixation device. At least one of the components of the device may
allow a screw or compressive member to be attached along its axis
to provide linear compression of one side of the fractured bone
towards the other (e.g. compression of the distal segment towards
the proximal segment or visa versa). At least one of the components
of the device may accept a screw at an acute angle, and angle less
than 30 degrees from the axis of the device that would allow
compression of one side of the fractured bone towards the other. At
least one of the components of the device may accept an alternately
removable eyelet to accommodate a compressive device so as to
compress one side of the fractured bone towards the other side.
In some embodiments, to aid in insertion into the intramedullary
canal, the main component of the fracture fixation device has a
substantially flexible state. Thereby, the device, prior to
activation, may not have a rigid section. Once in place, deployment
of the device also causes the components to change from the
flexible state to a rigid state to aid in proper fixation of the
fracture. At least one of the components may be semi-flexible.
Placement of the device may be aided by a detachable rigid member
such as a guide or outrigger. Placement of the device may be aided
by a removable rigid member such as a tube or guide wire. At least
one component may provide a bone screw attachment site for the
fixation device. At least one of the components of the device may
allow a screw or compressive member to be attached along its axis
to provide linear compression of one side of the fractured bone
towards the other (e.g. compression of the distal segment towards
the proximal segment or visa versa). At least one of the components
of the device may accept a screw at an acute angle, and angle less
than 30 degrees from the axis of the device that would allow
compression of one side of the fractured bone towards the other. At
least one of the components of the device may accept an alternately
removable eyelet to accommodate a compressive device so as to
compress one side of the fractured bone towards the other side.
Embodiments of the invention also provide deployment tools with a
tool guide for precise alignment of one or more bone screws with
the fracture fixation device. These embodiments also provide bone
screw orientation flexibility so that the clinician can select an
orientation for the bone screw(s) that will engage the fixation
device as well as any desired bone fragments or other bone or
tissue locations.
These and other features and advantages of the present invention
will be understood upon consideration of the following detailed
description of the invention and the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
The novel features of the invention are set forth with
particularity in the appended claims. A better understanding of the
features and advantages of the present invention will be obtained
by reference to the following detailed description that sets forth
illustrative embodiments, in which the principles of the invention
are utilized, and the accompanying drawings of which:
FIG. 1 is a perspective view of an embodiment of a bone fixation
device implanted in a bone according to the invention.
FIG. 2 is another perspective view of the implanted device of FIG.
1.
FIG. 3 is a longitudinal cross-section view of the bone fixation
device of FIG. 1 in a non-deployed state.
FIG. 4 is a side view of one embodiment of a shape-conforming
flexible-to-rigid body portion.
FIG. 5A is a side view of another embodiment of a shape-conforming
flexible-to-rigid body portion.
FIG. 5B is a perspective view of yet another embodiment of a
shape-conforming flexible-to-rigid body portion.
FIG. 6A is a perspective view showing another body portion
embodiment having interlocking features.
FIG. 6B is a longitudinal cross-sectional view of the body portion
shown in FIG. 6A.
FIG. 6C is a perspective view showing another body portion
embodiment having interlocking features.
FIG. 6D is a longitudinal cross-sectional view of the body portion
shown in FIG. 6C.
FIG. 6E is a perspective view showing another body portion
embodiment having interlocking features.
FIG. 6F is a longitudinal cross-sectional view of the body portion
shown in FIG. 6E.
FIG. 6G is a perspective view showing another body portion
embodiment having interlocking features.
FIG. 6H is a longitudinal cross-sectional view of the body portion
shown in FIG. 6G.
FIG. 6I is a perspective view showing another body portion
embodiment having interlocking features.
FIG. 6J is a longitudinal cross-sectional view of the body portion
shown in FIG. 6I.
FIG. 7A is a cross-sectional view showing the proximal end of a
device employing the body portion of FIG. 4, the device being shown
in a flexible state.
FIG. 7B is a cross-sectional view showing the proximal end of a
device employing the body portion of FIG. 4, the device being shown
in a shape-conforming state.
FIG. 8A is a side view showing a device employing two body portions
of FIG. 4, the device being shown in a flexible state.
FIG. 8B is a cross-sectional view showing a device employing two
body portions of FIG. 4, the device being shown in a flexible
state.
FIG. 8C is a cross-sectional view showing a device employing two
body portions of FIG. 4, the device being shown in a
shape-conforming state.
FIG. 8D is a partially exploded perspective view showing a device
employing two body portions of FIG. 5B, the device being shown in a
flexible state.
FIG. 8E is a cross-sectional view showing a device employing two
body portions of FIG. 5B, the device being shown in a flexible
state.
FIG. 9 is plan view depicting a device similar to that of FIGS.
8A-8C, the device being shown deployed in a clavicle.
FIG. 10 is a perspective view showing a device similar to that of
FIGS. 8A-8C, the device being introduced into the intramedullary
space of a clavicle.
FIG. 11 is a side view showing an alternative embodiment device in
a deployed, shape-conforming state and having alternative
anchors.
FIG. 12 is a side view showing another alternative embodiment
device in a deployed, shape-conforming state.
FIG. 13 is a perspective view showing another exemplary embodiment
of a bone fixation device attached to tools that may be used for
its insertion, deployment, and removal.
FIG. 14 is an exploded view showing the components of the bone
fixation device and insertion/removal tool of FIG. 13.
FIG. 15 is an enlarged perspective view showing the bone fixation
device of FIG. 13.
FIG. 16 is an enlarged, cut-away perspective view showing internal
components of the device of FIG. 13.
FIGS. 17A-17D are enlarged perspective views showing details of
various components of the device of FIG. 13.
FIG. 17E is a plan view showing an exemplary interlocking pattern
that may be used in the device of FIG. 13.
FIG. 18 is a longitudinal cross-section view showing the device and
a portion of the tools of FIG. 13.
FIG. 19 is a perspective view showing the device of FIG. 13 in a
deployed state.
FIG. 20 is a cut-away perspective view showing the device and tools
of FIG. 13 with a guide wire inserted therethrough.
FIG. 21 is an enlarged cross-section view showing the device, tools
and guide wire of FIG. 20.
FIGS. 22 and 23 are plan views showing exemplary patterns that may
be used in the flexible-to-rigid body portions of bone fixation
devices.
FIGS. 24A-24H are views showing an overlapping flexible-to-rigid
body portion, where FIG. 24A is a plan view, FIG. 24B is an
enlarged cross-sectional side view of the body portion in an
expanded, flexible state, FIG. 24C is an enlarged cross-sectional
side view of the body portion in a compressed, rigid state, and
FIGS. 24D-24H are enlarged plan views showing various tip
configurations.
FIGS. 25A-25C are views showing an exemplary flexible-to-rigid body
portion having an oval cross-section, where FIG. 25A is a side view
showing the device in a flexible state, FIG. 25B is a side view
showing the device in a rigid state, and FIG. 25C is a
cross-section taken along line 25C-25C in FIG. 25A.
FIGS. 26A-26C are views showing an exemplary flexible-to-rigid body
portion having a square cross-section, where FIG. 26A is a side
view showing the device in a flexible state, FIG. 26B is a side
view showing the device in a rigid state, and FIG. 26C is a
cross-section taken along line 26C-26C in FIG. 26A.
FIGS. 27A-27E show an alternative embodiment of a bone fixation
device.
FIGS. 28A-28E show an alternative embodiment of a bone fixation
device.
FIGS. 29A-29B show an alternative embodiment of a bone fixation
device.
DETAILED DESCRIPTION OF THE INVENTION
By way of background and to provide context for the invention, it
may be useful to understand that bone is often described as a
specialized connective tissue that serves three major functions
anatomically. First, bone provides a mechanical function by
providing structure and muscular attachment for movement. Second,
bone provides a metabolic function by providing a reserve for
calcium and phosphate. Finally, bone provides a protective function
by enclosing bone marrow and vital organs. Bones can be categorized
as long bones (e.g. radius, femur, tibia and humerus) and flat
bones (e.g. skull, scapula and mandible). Each bone type has a
different embryological template. Further each bone type contains
cortical and trabecular bone in varying proportions. The devices of
this invention can be adapted for use in any of the bones of the
body as will be appreciated by those skilled in the art.
Cortical bone (compact) forms the shaft, or diaphysis, of long
bones and the outer shell of flat bones. The cortical bone provides
the main mechanical and protective function. The trabecular bone
(cancellous) is found at the end of the long bones, or the
epiphysis, and inside the cortex of flat bones. The trabecular bone
consists of a network of interconnecting trabecular plates and rods
and is the major site of bone remodeling and resorption for mineral
homeostasis. During development, the zone of growth between the
epiphysis and diaphysis is the metaphysis. Finally, woven bone,
which lacks the organized structure of cortical or cancellous bone,
is the first bone laid down during fracture repair. Once a bone is
fractured, the bone segments are positioned in proximity to each
other in a manner that enables woven bone to be laid down on the
surface of the fracture. This description of anatomy and physiology
is provided in order to facilitate an understanding of the
invention. Persons of skill in the art will also appreciate that
the scope and nature of the invention is not limited by the anatomy
discussion provided. Further, it will be appreciated there can be
variations in anatomical characteristics of an individual patient,
as a result of a variety of factors, which are not described
herein. Further, it will be appreciated there can be variations in
anatomical characteristics between bones which are not described
herein.
FIGS. 1 and 2 are perspective views of an embodiment of a bone
fixation device 100 having a proximal end 102 (nearest the surgeon)
and a distal end 104 (further from surgeon) and positioned within
the bone space of a patient according to the invention. In this
example, device 100 is shown implanted in the upper (or proximal)
end of an ulna 106. The proximal end and distal end, as used in
this context, refers to the position of an end of the device
relative to the remainder of the device or the opposing end as it
appears in the drawing. The proximal end can be used to refer to
the end manipulated by the user or physician. The distal end can be
used to refer to the end of the device that is inserted and
advanced within the bone and is furthest away from the physician.
As will be appreciated by those skilled in the art, the use of
proximal and distal could change in another context, e.g. the
anatomical context in which proximal and distal use the patient as
reference.
When implanted within a patient, the device can be held in place
with suitable fasteners such as wire, screws, nails, bolts, nuts
and/or washers. The device 100 is used for fixation of fractures of
the proximal or distal end of long bones such as intracapsular,
intertrochanteric, intercervical, supracondular, or condular
fractures of the femur; for fusion of a joint; or for surgical
procedures that involve cutting a bone. The devices 100 may be
implanted or attached through the skin so that a pulling force
(traction may be applied to the skeletal system).
In the embodiment shown in FIG. 1, the design of the metaphyseal
fixation device 100 depicted is adapted to provide a bone engaging
mechanism or gripper 108 adapted to engage target bone of a patient
from the inside of the bone. As configured for this anatomical
application, the device is designed to facilitate bone healing when
placed in the intramedullary space within a post fractured bone.
This device 100 has a gripper 108 positioned distally and shown
deployed radially outward against the wall of the intramedullary
cavity. On entry into the cavity, gripper 108 is flat and retracted
(FIG. 3). Upon deployment, gripper 108 pivots radially outward and
grips the diaphyseal bone from the inside of the bone. One or more
screws 110 placed through apertures through the hub 112 lock the
device 100 to the metaphyseal bone. Hence, the metaphysis and the
diaphysis are joined. A flexible-to-rigid body portion 114 may also
be provided, and in this embodiment is positioned between gripper
108 and hub 112. It may be provided with wavy spiral cuts 116, for
example, for that purpose as will be described in more detail
below.
FIG. 3 shows a longitudinal cross-section of device 100 in a
non-deployed configuration. In this embodiment, gripper 108
includes two pairs of opposing bendable members 118. Two of the
bendable members 118 are shown in FIG. 3, while the other two (not
shown in FIG. 3) are located at the same axial location but offset
by 90 degrees. Each bendable member 118 has a thinned portion 120
that permits bending as the opposite distal end 122 of member 118
is urged radially outward, such that member 118 pivots about
thinned portion 120. When extended, distal ends 122 of bendable
members 118 contact the inside of the bone to anchor the distal
portion of device 100 to the bone. In alternative embodiments (not
shown), the gripper may comprise 1, 2, 3, 4, 5, 6 or more bendable
members similar to members 118 shown. Hence, the proximal end and
or metaphysis and the distal end and or diaphysis are joined. The
union between the proximal and distal ends may be achieved by the
grippers, 108, alone or in concert with screws 110 placed through
hub 112. Hub 112 may be either at the distal or proximal end of the
bone, in this case the ulna. A hub 112 may be at both ends of the
device, there by allowing screws to be placed in the distal and
proximal ends. A flexible-to-rigid body portion 114 may also be
provided, and in this embodiment is positioned between grippers 108
and 109. The flexible-to-rigid body portion may be placed proximal
or distal to both sets of grippers, 108. In some embodiments,
gripper 109 may be made of a nickel-titanium alloy.
During actuation, bendable members 118 of gripper 108 are urged
radially outward by a ramped surface on actuator head 124. Actuator
head 124 is formed on the distal end of actuator 126. The proximal
end of actuator 126 is threaded to engage a threaded bore of drive
member 128. The proximal end of drive member 128 is provided with a
keyed socket 130 for receiving the tip of a rotary driver tool (not
shown) through the proximal bore of device 100. As rotary driver
tool turns drive member 128, actuator 126 is drawn in a proximal
direction to outwardly actuate gripper members 118. In an
alternative embodiment, actuator 126 may be made of a super elastic
alloy that when released from its insertion state it returns to its
unstressed state thereby driving grippers 108 and 109 outward,
shortening the device thereby compressing 518 into a rigid
state.
Gripper 108 and the actuator head 124 may be reversed in their
geometrical layout of the device. The gripper 108 may be drawn by
the actuator 126 over the actuator head 124, thereby deflecting the
bendable members, 118, outward. Similarly, the bendable members,
118, may be made of a super elastic or elastic or spring alloy of
metal whereby the bendable members are predisposed in their set
state in the insertion configuration, that being their smallest
diameter. When the actuator head, 124, engages the super elastic,
elastic or spring alloy of steel bendable members 118, a continuous
force is imparted upon actuator head 124 such that the bendable
members 118 return to their insertion geometry after the actuator
head 124 is removed. Typical super elastic, elastic, or spring
alloys of metals include spring steels and NiTi or nitinol.
Conversely, bendable members 118 may be made of super elastic,
elastic, or spring alloys of metal and set in their maximum outside
diameter, in their deployed state. Actuator 124 and the rectangular
apertures in 518 would work cooperatively to expose the bendable
members 118. Since the bendable members 118 would be set in their
maximum outside dimension and constrained within 518, upon exposure
of 118 to the rectangular apertures, the bendable members would be
driven by the material properties into the bone.
A hemispherical tip cover 134 may be provided at the distal end of
the device as shown to act as a blunt obturator. This arrangement
facilitates penetration of bone by device 100 while keeping the tip
of device 100 from digging into bone during insertion. The tip may
have various geometrical configurations that adapt to enabling
tools such as guide wires and guide tubes. The tip may be actively
coupled to an electrical or mechanical source that removes or
ablates bone to facilitate insertion.
As previously mentioned, device 100 may include one or more
flexible-to-rigid body portions 114. This feature is flexible upon
entry into bone and rigid upon application of compressive axial
force provided by tensioning actuator 126. Various embodiments may
be used, including dual helical springs whose inner and outer
tubular components coil in opposite directions, a chain of ball
bearings with flats or roughened surfaces, a chain of cylinders
with flats, features, cones, spherical or pointed interdigitating
surfaces, wavy-helical cut tubes, two helical cut tubes in opposite
directions, linear wires with interdigitating coils, and
bellows-like structures.
The design of the flexible-to-rigid tubular body portion 114 allows
a single-piece design to maximize the transformation of the same
body from a very flexible member that minimizes strength in bending
to a rigid body that maximizes strength in bending and torque. The
flexible member transforms to a rigid member when compressive
forces are applied in the axial direction at each end, such as by
an actuator. The body portion 114 is made, for example, by a
near-helical cut 116 on a tubular member at an angle of incidence
to the axis somewhere between 0 and 180 degrees from the
longitudinal axis of the tubular body portion 114. The near-helical
cut or wavy-helical cut may be formed by the superposition of a
helical curve added to a cyclic curve that produces waves of
frequencies equal or greater than zero per turn around the
circumference and with cyclic amplitude greater than zero. The
waves of one segment nest with those on either side of it, thus
increasing the torque, bending strength and stiffness of the
tubular body when subjective to compressive forces. The tapered
surfaces formed by the incident angle allow each turn to overlap
with the segment on either side of it, thus increasing the bending
strength when the body is in compression. Additionally, the cuts
can be altered in depth and distance between the cuts on the
longitudinal axis along the length of body portion 114 to variably
alter the flexible-to-rigid characteristics of the tubular body
along its length.
The cuts 116 in body portion 114 allow an otherwise rigid member to
increase its flexibility to a large degree during deployment. The
tubular member can have constant or varying internal and external
diameters. This design reduces the number of parts of the
flexible-to-rigid body portion of the device and allows insertion
and extraction of the device through a curved entry port in the
bone while maximizing its rigidity once inserted. Application and
removal of compressive forces provided by a parallel member such as
wire(s), tension ribbons, a sheath, or actuator 126 as shown will
transform the body from flexible to rigid and vice versa.
In operation, as actuator 126 is tightened, gripper members 118 are
extended radially outwardly. Once the distal ends of gripper
members 118 contact bone and stop moving outward, continued
rotation of actuator 126 draws the proximal end 102 and the distal
end 104 of device 100 closer together until cuts 116 are
substantially closed. As this happens, body portion 114 changes
from being flexible to rigid to better secure the bone fracture(s),
as will be further described below. Rotating actuator 126 in the
opposite direction causes body portion 114 to change from a rigid
to a flexible state, such as for removing device 100 if needed in
the initial procedure or during a subsequent procedure after the
bone fracture(s) have partially or completely healed. Body portion
114 may be provided with a solid longitudinal portion 136 (shown in
FIG. 3) such that cuts 116 are a series of individual cuts each
traversing less than 360 degrees in circumference, rather than a
single, continuous helical cut. This solid portion 136 can aid in
removal of device 100 by keeping body portion 114 from undesirably
extending like a spring. One or more internal tension members (not
shown) may also be used to limit the extension of body portion 114
when it is in tension. In an alternative embodiment, actuator 126
may be made of a super elastic alloy that when released from its
insertion state it returns to its unstressed state thereby driving
grippers 108 and 109 outward, shortening the device thereby
compressing 518 into a rigid state. To some one skilled in the art,
the gripper 108 and the actuator head 124 can be reversed in their
geometrical layout of the device. The gripper 108 could be drawn by
the actuator 126 over the actuator head 124, thereby deflecting the
bendable members, 118, outward. Similarly, the bendable members,
118, may be made of a super elastic or elastic or spring alloy of
metal where by the bendable members are predisposed in their set
state in the insertion configuration, that being their smallest
diameter. When the actuator head, 124, engages the super elastic,
elastic or spring alloy of steel bendable members, 118, a
continuous force is imparted upon actuator head 124 such that the
bendable members 118, return to their insertion geometry after the
actuator head 124 is removed. Typical super elastic, elastic, or
spring alloys of metals include spring steels and NiTi or nitinol.
Conversely, bendable members 118 may be made of super elastic,
elastic, or spring alloys of metal and set in their maximum outside
diameter, in their deployed state. Actuator 124 and the rectangular
apertures in 518 would work cooperatively to expose the bendable
members 118. Since the bendable members 118 would be set in their
maximum outside dimension and constrained within 518, upon exposure
of 118 to the rectangular apertures, the bendable members would be
driven by the material properties into the bone.
FIGS. 4, 5A and 5B show various exemplary embodiments of anatomy or
shape conforming body portions constructed according to aspects of
the present invention. These and other body portions may be used in
bone fixation devices similar to those described above. These body
portions may be used in place of body portion 114 previously
described to allow the device to take on a shape that conforms to a
particular anatomy when the body of the device is axially
compressed when making the device substantially rigid.
Referring first to FIG. 4, flexible-to-rigid tubular body portion
114' includes a first side 410 which forms a solid spine and a
second side 412 which has a series of straight, V-shaped cuts 414
in it. In this embodiment, the V-shaped cuts 414 extend a
substantial portion of the way across the diameter of tubular body
portion 114'. As body portion 114' is axially compressed in manner
similar to body portion 114 previously described, the first side
410 retains its original length because it is solid. The second
side 412, however, is foreshortened as V-shaped cuts 414 begin to
close. With this difference in lengths between sides 410 and 412,
body portion 114' takes on a curved shape, with first side 410
becoming convex and second side 412 becoming concave. The curved
configuration of body portion 114' can be designed to match the
curve of an intramedullary bone cavity where the body portion 114'
is being implanted.
FIG. 5A shows another embodiment of a flexible-to-rigid tubular
body portion 114''. Body portion 114'' has a first side 510, a
second side 512, and a series of wavy slits 514. Slits 514 may be
individual slits extending partially around the circumference of
body portion 114'', leaving a solid spine near first side 510,
similar to first side 410 shown in FIG. 4. Alternatively, slits 514
may extend completely around the circumference of body portion
114', creating a series of solid wavy rings therebetween. In yet
another alternative, slits 514 may extend completely around the
circumference of body portion 114'' in spiral fashion to create one
continuous helical slit.
As can be seen in FIG. 5A, slits 514 have a varying width that
increases as they extend from first side 510 to second side 512.
With this configuration, second side 512 will foreshorten more than
first side 510 as slits 514 close during axial compression. This
results in body portion 114'' taking on a curved shape, with first
side 510 becoming convex and second side 512 becoming concave. The
alternating curves of slits 514 provide increased torsional
rigidity, particularly when body portion 114'' is axially
compressed.
FIG. 5B shows yet another embodiment of a flexible-to-rigid tubular
body portion 114'''. Body portion 114''' has a first side 610, a
second side 612, and a series of wavy slits 614. First side 610
forms a solid spine that does not axially compress. In this
embodiment, slits 614 have a generally uniform width. During axial
compression, body portion 114''' takes on a curved shape, with
first side 610 becoming convex and second side 612 becoming
concave.
Alternative designs (not shown), such as wave patterns of an
interdigitating saw tooth or square wave, and the like, are also
contemplated for increased torsional rigidity. As described above,
these patterns may form discrete rings around body portion 114, or
these patterns may be superimposed on a helical curve to form a
continuous spiral pattern.
FIGS. 6A-6J show further exemplary embodiments of anatomy or shape
conforming body portions constructed according to aspects of the
present invention. Similar to the body portions described above,
the body portions shown in FIGS. 6A-6J may be used in place of body
portion 114 previously described to allow an implantable bone
fixation device to take on a shape that conforms to a particular
anatomy when the body of the device is axially compressed when
making the device substantially rigid. The body portions shown in
FIGS. 6A-6J have interlocking appendages or features that allow
each body portion to transform from a generally flexible state to a
generally rigid state when axial compression is applied. Like some
of the body portions described above, these interlocking features
also permit the transmission of torsional forces in both the
flexible and rigid states of the device. Being able to transmit
torsional forces without excessive rotational displacement from one
end of the implantable device to the other can be advantageous in
various situations, such as during insertion or removal of the
device, or when a surgeon desires to rotate the device to properly
align it during installation in a bone. Additionally, the
interlocking features of the exemplary embodiments shown are
designed to resist tensile forces. This allows the surgeon to pull
on the proximal end of the device without the device uncoiling or
extending excessively in length.
As seen in the flexible-to-rigid body portion shown in FIGS. 6A and
6B, the interlocking features can comprise an alternating trapezoid
or dovetail pattern 650 superimposed on a helical curve. As shown
in FIGS. 6C and 6D, the interlocking features can comprise an omega
shape 660. FIGS. 6E and 6F show that the interlocking features can
comprise bulbous pendicles 670. FIGS. 6G and 6H show that the
interlocking features can comprise an L-shape 680. Note that the
gap 682 between features in one column is wider than gap 684 in the
adjacent column, which in turn is wider than gap 686 in the next
column. This progressive widening of gaps from one side of the
flexible to rigid body portion to the other causes the body portion
to curve when compressed, as will be further described below. FIGS.
6I and 6J show an example of T-shaped interlocking features 690. In
other embodiments, a pattern of interlocking features can be
continuous or intermittent. The interlocking features may also vary
in a radial direction across the tube wall, and/or in an axial
direction rather than, or in addition to, varying across the
circumference of the tube as shown in FIGS. 6A-6J.
The body portions shown in FIGS. 6A-6J need not be curved when
axially compressed as described above. Rather, they may be designed
so that they compress equally on all sides of the center axis such
that they form a straight segment when either flexible or rigid.
Alternatively, the body portions may be designed to be curved when
flexible, and compress in a uniform fashion such that they maintain
their curved shape when transformed to a generally rigid state.
FIGS. 6A-6J provide exemplary geometries for a variety of cut
patterns. The cross sectional geometry is shown as tubular. As
discussed in more detail below, the cross sectional area can be of
any shape tubular geometry or solid geometry. The specific cut
pattern and cross sectional shape are selected and designed to
match the anatomical shape of the bone or to provide specific
fixation or reconstructive surfaces particularly suited to
remediate the problem with the bone. Different cross sectional
geometries are needed for the flat bones found in the face and
skull, the ribs, the tibial plateau, the metacarpals, the
metatarsals, and the scaphoid bone of the hand. The cut pattern can
be "programmed" to reconstruct the bone into its anatomical
configuration or into a modified configuration based upon the
desired result of the remediation therapy. For instance, a
reconstructive procedure may be prescribed to remediate a malunion
of a bone. In this example the device, rather than collapsing upon
activation lengthens and becomes rigid.
Although shown in the various embodiments of the figures is a
device with grippers, it is also envisioned that the
flexible-to-rigid member would collapse or extend such that axially
successive geometries would be upset and driven radially outward.
In is flexible state the cut patterns would freely bend relative to
each other. Upon activation to the rigid state, for example, a
crest of a wave pattern would be urged outward, thereby increasing
the effective diameter of the device. The crest of the wave could
be forced into the intramedullary bone and create a fixation
moiety. One could envision a long tube where the crests of the wave
patterns would be drive outward there by creating a high surface
area of gripping power over the entire length of the device. Other
pattern besides wave patterns could be made to do this.
FIGS. 7A and 7B depict the proximal end of a device 100' which is
similar to device 100 previously described but incorporating the
flexible-to-rigid tubular body portion 114' of FIG. 4. FIG. 7A
shows device 100' in a flexible, undeployed state, and FIG. 7B
shows device 100' in a generally rigid, curved state. To change
between states after device 100' is inserted in the intramedullary
cavity of a bone, the tip of a rotary driver tool (not shown) is
inserted in keyed socket 130 of drive member 128' and rotated.
Drive member 128' is threadably engaged with shuttle 710. Shuttle
710 may be constructed in a flexible manner such that body portion
114' remains flexible when in the undeployed state of FIG. 7A.
Shuttle 710 may include a tab 712 at its proximal end that travels
in slot 714 in the tube wall to prevent shuttle 710 from rotating
(as best seen in FIG. 8D). As drive member 128' is rotated by the
driver tool, shuttle 710 is drawn towards the proximal end of
device 100', as shown in FIG. 7A. The proximal end of a tension
wire 716 in turn is rigidly attached to shuttle 710. The distal end
of tension wire 716 (not shown) may be coupled to a distal gripper
as previously described, or attached to the distal end of device
100'. When tension wire 716 is drawn proximally by shuttle 710,
V-shaped gaps 414 on the second side 412 of body portion 114' are
closed, causing body portion 114' to assume a curved shape as shown
in FIG. 7B.
FIGS. 8A-8C show an alternative embodiment device 100'' in various
states. FIG. 8A shows device 100'' in a non-tensioned state, FIG.
8B shows a cross-section of device 100'' in the non-tensioned
state, and FIG. 8C shows a cross-section of device 100'' in a
tensioned state.
Device 100'' includes two flexible-to-rigid tubular body portions
114', 114' oriented in opposite directions. With this
configuration, when shuttle 710 and tension wire 716 are drawn
proximally by rotating drive member 128, device 100'' assumes an
S-shape, as shown in FIG. 8C. Thus, device 100'' may be used to
repair S-shaped bones such as the clavicle. In a similar manner,
the axial width, axial pitch and/or radial orientation of V-shaped
cuts 414 can be varied to produce compound, varying curves in three
dimensions to match any desired anatomy. For obtaining smaller
radii of curvature, V-shaped cuts 414 that are more blunt may be
used. The flexible to rigid body portions need not be of identical
cross section. For example a round tubular section could be paired
with a hexagonal tubular section. This would allow one section to
rotate freely within the space it is located where the hexagonal
structure would provide a form of resistance or registration.
FIGS. 8D and 8E show an S-forming device 100'''similar to device
100'' shown in FIGS. 8A-8C, but having wavy slits 614 instead of
straight V-shaped cuts 414.
FIG. 9 depicts an S-shaped device similar to device 100'' deployed
in a clavicle bone 910 across a mid-shaft fracture 912. Device 101
may be configured with a gripper 108 and/or one or more screw holes
914 at its proximal end to secure device 101 to one half of
clavicle 910. Similarly, device 101 may be configured with a
gripper 108 and/or one or more screw holes 914 at its distal end to
secure device 101 to the other half of clavicle 910. Body portions
114', 114' are configured such that they are flexible when being
introduced into clavicle 910. When grippers 108, 108 are deployed
and body portions 114', 114' become rigid as described above,
device 101 assumes an S-shape that closely matches the contour of
the intramedullary cavity within clavicle 910. Such a configuration
allows device 101 to more rigidly support clavicle 910 for healing
of fracture 912 while avoiding undue forces on clavicle 910.
FIG. 10 shows device 101 described above and depicted in FIG. 9 as
it is being introduced into a fractured clavicle 910.
FIG. 11 shows an alternative shape conforming device 103. Device
103 forms a simple curve when flexible-to-rigid body portion 114''
(also shown in FIG. 5A) is in a rigid state. Device 103 includes a
gripper 108' at its distal end, having opposing tube segments 1110,
1110 that rotate to engage the bone when gripper 108' is deployed.
Device 103 also has a tripod gripper 108'' at its proximal end,
having three pairs of scissor arms 1112, 1112, 1112 for engaging
the bone when actuated. Further details of grippers 108' and 108''
are provided in copending application Ser. No. 11/944,366
referenced above.
FIG. 12 shows an alternative shape conforming device 105. As shown,
device 105 forms an S-shape when flexible-to-rigid body portions
114'' are in a rigid state. The distal end of device 105 may be
secured to the bone by gripper 108, and the proximal end may be
secured with bone screws through the device, as shown in FIGS. 1
and 2.
In alternative embodiments (one of which will be described below),
grippers 108 and screw 110 attachment provisions may be omitted
from one or both ends of the device. In these embodiments, the
curved nature of body portion(s) 114' is enough to secure the
device end(s) within the bone and hold the fracture(s) in place. In
embodiments with and without grippers 108 and screws 110, the
anatomy-conforming curve may serve to grip the bone and approximate
the fracture(s). In many embodiments, the action of the closing of
the slots (such as 116) during axial compression also serves to
grip the bone and/or approximate the fracture(s). In other
embodiments, wire or other fastening elements may be used to secure
the device in place.
Referring now to FIGS. 13-21, another exemplary embodiment of a
bone fixation device constructed according to aspects of the
present invention will be described. FIG. 13 shows bone fixation
device 1300 attached to an insertion and removal tool 1302 and
actuation tool 1304. Insertion and removal tool 1302 in turn is
mounted in a fixture arm 1306.
Referring to FIG. 14, components of bone fixation device 1300 and
insertion and removal tool 1302 are shown. In this exemplary
embodiment, device 1300 comprises a hub 1402, actuation screw 1404,
actuation shuttle 1406, flexible-to-rigid body member(s) 1408,
tension member 1410, and end cap 1412. In alternative embodiments,
additional, fewer, or a single flexible-to-rigid body member may be
used. Insertion and removal tool 1302 comprises sleeve 1450, tube
1452, knob 1454, and may be mounted though fixture arm 1306.
Referring to FIG. 15, an enlarged perspective view of the assembled
device 1300 is shown.
Referring to FIG. 16, an enlarged, cut-away perspective view shows
internal components of device 1300. End cap 1412, having the same
nominal outer diameter as flexible-to-rigid body member(s) 1408
(shown in FIG. 15), is rigidly connected, such as by welding, to
the distal end of tension member 1410. Tension member 1410 is sized
to fit within flexible-to-rigid body member(s) 1408. Tension member
1410 may include a central longitudinal lumen, the purpose of which
is later described. Tension member 1410 may also be provided with a
series of longitudinal slots 1610 through its wall thickness to
allow it to be very flexible. Solid ring portions 1612 may be
interspersed between the series of slots 1610 to retain the tubular
shape and torsional rigidity of tension member 1410. In other
embodiments (not shown), the tension member is formed from one or
more wires or cables, which may be bundled together, to be strong
in tension while being flexible in bending.
Actuation shuttle 1406 is attached to the proximal end of tension
member 1410, such as by welding. Actuation shuttle 1406 includes a
knobbed end 1710, as best seen in FIG. 17A. Knobbed end 1710 is
configured to be received within mating keyhole 1712 in one side of
actuation screw 1404, as best seen in FIGS. 17B and 17C. Actuation
shuttle 1406 may also include a radially-protruding tab 1714, as
best seen in FIG. 17A. Tab 1714 is sized to slide in a longitudinal
slot 1510 in device hub 1402, as best seen in FIG. 15, to allow
actuation shuttle 1406 to move axially without rotation. With
actuation shuttle 1406 rotatably received in actuation screw 1404,
which in turn is threadably engaged with hub 1402, the distal end
of actuation tool 1304 may be received (as best seen in FIG. 18) in
a keyed recess 1716 (best seen in FIG. 17C) of actuation screw
1404. Turning actuation screw 1404 with actuation driver 1304
causes actuation screw 1404, and with it actuation shuttle 1406, to
move axially with respect to hub 1402. As actuation shuttle 1406
moves in a proximal direction (away from distal end cap 1412), a
tensile force is imparted to tension member 1410, causing
flexible-to-rigid body member(s) 1408 to be axially compressed
between end cap 1412 and hub 1402 (see FIGS. 15 and 16). As
previously described, this compression causes body member(s) 1408
to become substantially rigid, and to take on a predetermined
shape, as will be more fully described below.
Referring to FIG. 17E, a plan view of an interlocking pattern is
shown. The pattern has the same interlocking L-shaped features 680
as the flexible-to-rigid body member 1408 shown in FIGS. 6G and 6H
described briefly above. In other words, FIG. 17E represents the
pattern that would result if the body member 1408 were slit along
one side in a longitudinal direction, unrolled and laid flat.
Arrows 1710 in FIG. 17E indicate the longitudinal or axial
direction of the pattern, while arrows 1712 represent the
tangential direction. As can be seen, the pattern is formed by a
continuous helical cut, such that gap 1722 on one side of the
pattern connects with gap 1724 on the other side of the pattern
when the pattern is formed on a tubular structure. While a single
helical cut is shown, other embodiments may employ two or more
helical cuts running in parallel around the tube. Pattern gaps may
be formed by laser cutting, punching, milling, etching, sawing,
electro-discharge machining, or other material removal or material
addition processes. Patterns may be formed on a tubular structure,
or on a generally flat substrate which is then configured into a
tubular structure.
As briefly mentioned above in conjunction with FIG. 6G, the
interlocking pattern may utilize gaps that narrow along one side of
the tube (shown in the center of FIG. 17E) and widen along the
other side of the tube (shown at the sides of FIG. 17E). In this
exemplary pattern, gaps 682 are wider than gaps 684, which in turn
are wider than gaps 686, which in turn are wider than gap 1726. As
the pattern is compressed in an axial direction when formed on a
tubular structure, the features adjacent the wider gaps (e.g. 682)
will move farther than the features adjacent the narrower gaps
(e.g. 1726) as the gaps are closed. Since one side of the tube is
compressing more than the opposite side, the tube forms a curve
that is concave on the side having the widest gaps.
Referring again to FIGS. 14 and 15, and also to FIG. 18, if all of
the flexible-to-rigid body members 1408 are oriented with their
widest pattern gaps on one side of the device 1300, the
flexible-to-rigid portion will take on a single curved shape. If
the body members 1408 toward the distal end are all oriented with
their widest pattern gaps on one side, and the body members 1408
toward the proximal end are all oriented with their widest gaps on
the opposite side, a compound or S-shaped curve will result, as
shown in FIG. 19. If the orientation of each successive body member
is alternated from one side to the other and back again, a rapidly
undulating curve will result. If the orientation of each successive
body member is changed in phase, for example by 90 degrees, from
the orientation of the previous body member, a helical arrangement
of the overall flexible-to-rigid body portion may be achieved. It
can be appreciated that by changing the orientation of the gap
thicknesses, essentially any desired three-dimensional curve may be
obtained to suit the particular purpose. For example, the rapidly
undulating curve described above may be more useful in some
circumstances for allowing a bone fixation device to gain purchase
within a relatively straight intramedullary canal. A body member
having a compound curve can be useful in a bone fixation device
that is designed to be inserted in a radius or an ulna, as these
bones curve in more than one plane simultaneously. A bone fixation
device having an S-shaped curve is useful in bones that have
S-shaped portions, such as the clavicle.
It should be noted that in addition to varying the gap orientation,
the relative change in gap width may be varied to produce curves of
different radii. For example, one portion of a flexible-to-rigid
body may have the same gap width around its circumference to
produce a straight section, another portion may have a relatively
small change in gap width to produce a large radius of curvature,
while yet another portion may have a larger change in gap width
around its circumference to produce a small radius of curvature. In
some embodiments, such as shown in the accompanying figures, the
device may employ a series of individual body members 1408 that
together form an overall flexible-to-rigid body portion.
Alternatively, it should be noted again that a continuous complex
pattern similar to that formed by the multiple body sections
described above may be formed on a single tubular structure.
Additionally, interlocking or non-interlocking features other than
the L-shaped features 680 may be used in addition to or instead of
features 680.
Referring to FIGS. 20 and 21, use of the bone fixation device 1300
and associated tools with a guide wire 2010 is described. As
described above and shown in the accompanying figures, each of the
central components of device 1300 has an axial lumen extending
therethrough. Similarly, the central components of actuation tool
1304 have an axial lumen extending therethrough. This arrangement
permits device 1300, insertion/removal tool 1302, and/or actuation
tool 1304 to be slid, either individually or together, over guide
wire 2010.
In some bone fixation operations, it is advantageous to first
introduce a guide wire into the intramedullary space of a bone
before inserting a bone fixation device 1300, and in some cases
before preparing the intramedullary canal for receiving device
1300. According to aspects of the invention, in some methods an
access incision or puncture is made in the tissue surrounding a
bone. A pilot hole may then be drilled in the bone to gain access
to the intramedullary canal. Guide wire 2010 may then be introduced
through the pilot hole (or in some cases without a pilot hole) into
the intramedullary space. Guide wire 2010 may be further advanced
through the canal and across a fracture site or sites, lining up
bone fragments along the way. Introduction of guide wire 2010 may
take place with the aid of fluoroscopy or other imaging
technique.
After guide wire 2010 is inserted into a target bone, various burs,
cutters, reamers, trocars, and/or other bone forming or aligning
tools may be alternately advanced over guide wire 2010. One an
interior bone space has been prepared (if desired) to receive bone
fixation device 1300, device 1300 along with insertion/removal tool
1302 and actuation tool 1304 may be advanced over guide wire 1210.
Insertion/removal tool 1302 may first be inserted in fixture arm
1306, which in turn may be fastened to external fixtures or used as
a handle to assist in steadying and aligning device 1300 during
insertion and actuation. Device 1300 may then be advanced along
guide wire 2010 and into position within the bone. The guide wire
may occupy a central lumen of the device along its longitudinal
axis. The guide wire may slide along openings in the outer diameter
surface of the device in an analogous fashion to the eyelets of a
fishing rod. These lumen may be intra-operatively or
post-operatively available for the delivery of other devices,
therapies to the bone, or tools.
Deployment of device 1300 may be accomplished by rotating actuation
tool 1304. As previously described, such rotation moves actuation
screw 1404 in a proximal direction and ultimately causes a
compressive load to be placed on flexible-to-rigid body portion(s)
1408. This in turn causes flexible-to-rigid body portion(s) 1408 to
take on a desired shape and become generally rigid to secure device
1300 against the interior surfaces of the bone. Actuation tool 1304
may include a torque measuring or limiting mechanism to help ensure
that a predetermined or desired amount of force is being applied
from deployed device 1300 against the bone. Device 1300 may be
secured with additional methods, such as with bone screw(s),
K-wire(s) and the like.
Actuation tool 1304 and insertion/removal tool 1302 may be removed
together or individually. Actuation tool 1304 is removed be pulling
in a proximal direction to disengage its distal tip from recess
1716 within actuation screw 1404. Insertion/removal tool 1302 is
disengaged from device 1300 by turning the knob at the proximal end
of tool 1302. This unscrews the externally threaded distal tip of
tube 1452 of tool 1302 from the internally threaded bore of hub
1402, as best seen in FIG. 21. The guide wire 1210 may then be
removed (or at an earlier time if desired), and the access wound(s)
closed. It will be appreciated that these same tools and the
reverse of these methods may be used to remove device 1300, if
desired, during the initial procedure or at a later time.
Referring to FIGS. 22 and 23, additional exemplary patterns are
shown that may be used in the flexible-to-rigid body portions of
bone fixation devices. Non-repeating pattern 2200 includes ten
different interlocking shape pairs along a helical slit 2202, none
of which are the same. In this example pattern 2200, there are two
interlocking shape pairs located along each revolution of helical
slit 2202, such that when the pattern is formed on a tube, the two
pairs are on opposite sides of the tube. Alternatively, a pattern
of interlocking shapes may repeat every revolution of the helical
slit 2202, every partial revolution, or over the course of more
than one revolution. For example, a series of six different
interlocking shape pairs may repeat every three revolutions of
helical slit 2202, as shown in the exemplary pattern 2300 of FIG.
23.
It can be seen in FIGS. 22 and 23 that patterns 2200 and 2300
include ramped portions 2204 along each revolution of helical slit
2202 where the slit gets progressively wider. Additionally, helical
slit 2202 forms a wider gap adjacent to the lower set of
interlocking shape pairs 2206 than it does adjacent to the upper
set of shape pairs 2208. These ramped portions 2204 and wider gaps
allow patterns 2200 and 2300 to axially compress to a greater
extent in one area (the lower part of FIGS. 22 and 23) than in
another area (the upper part of FIGS. 22 and 23). Accordingly, when
patterns 2200 and 2300 are applied to a tubular member, the member
will form a curve when axially compressed, as previously
described.
Referring to FIGS. 24A-24H, an alternative flexible-to-rigid body
portion pattern 2400 will now be described. Pattern 2400 is formed
by superimposing a sinusoidal pattern on helical slit 2402. Helical
slit 2402 may be continuous, or it may be formed in individual
segments with solid sections in between, as shown in FIG. 24A. In
can be seen in FIG. 24A that the peak 2404 on one side of slit 2402
nests within trough 2406 on the opposite side of slit 2402.
Referring to FIG. 24B, it can be seen that slit 2402 may be formed
at an angle relative to tube wall 2408 rather than being
perpendicular to tube wall 2408 and the longitudinal axis of the
device. In this manner, a ramp is formed on the peak side 2404 of
slit 2402 and another ramp is formed on the trough side 2406. In
other embodiments, a ramp may be formed only on the peak side 2404
or only on the trough side 2406. In some embodiments, only a
portion of one or both sides is ramped or rounded. When the
flexible-to-rigid body portion is axially compressed, the ramps
cause at least a tip portion 2410 of peak 2404 to ride up on trough
2406 and extend radially outward, as shown in FIG. 24C. This tip
portion may be configured to bite into the surrounding bone. Even
if each extending tip 2410 only provides a small amount of gripping
force, with a large number of tips 2410 engaging the bone a large
amount of gripping power can be generated to hold the device within
the bone. In the embodiment shown in FIG. 24C, only a portion of
the tube wall 2408 on one side of slit 2402 rides above the tube
wall 2408 on the opposite side of slit 2402. In other embodiments,
one side of tube wall 2408 may ride up and completely onto the
opposite side.
Referring to FIGS. 24D-24G, tip 2410 need not take the shape of a
sinusoidal wave. The tip may be V-shaped (FIG. 24D), semicircular
(FIG. 24E), chisel-shaped (FIG. 24F), square (FIG. 24G), notched
(FIG. 24H), or have another shape in order to effectively grip the
surrounding bone. Tips of a particular device may have the same
shape on every tip, or multiple tip shapes may be used on one
device.
While bone fixation devices having circular cross-sections have
been shown and described, other cross-section shapes according to
aspects of the invention may be useful in some circumstances. In
some embodiments, a triangular cross-section may be used, as its
sharp edges can aid in gripping the surrounding bone. Non-circular
cross sections may be used in applications where a particular
combination of area moments of inertia is desired. Particular
non-circular cross sections may be chosen for their optimization in
certain anatomies, or for aiding in manufacturability of a bone
fixation device. In some embodiments, the cross section of the bone
fixation device is circular, oval, elliptical, triangular, square,
rectangular, hexagonal, octagonal, semi-circular, crescent-shaped,
star-shaped, I-shaped, T-shaped, L-shaped, V-shaped, or a
combination thereof. In some embodiments, the cross section forms a
polygon having any number of sides from 1 to infinity. In some
embodiments, the cross-sections are tubular and in others they are
solid. In some embodiments, the cross-section of the device can
vary in size along it length, such as tapering from the proximal
end to the distal end. FIGS. 25A-25D provide an example of an oval
cross section, and FIGS. 26A-26D provide an example of a square
cross-section.
In other embodiments, a solid rectangular geometry with an
externally communicating stiffening member can be constructed.
FIGS. 27A-27E, FIGS. 28A-28E and FIGS. 29A-29B describe three
exemplary geometries. The external stiffener geometry of the device
shown in FIGS. 27A-27E, and its resultant shape upon activation to
its rigid state, are designed to allow insertion, match the
anatomical configuration of the bone, and provide remediation of
the malady of the bone, such as proximation and fixation of the
fracture. The external stiffener geometry of the device allows
removal upon deactivation. The devices shown in FIGS. 27 through 29
may be used for treatment of flat bones, such as those of the face,
skull, scapula, and lateral clavicle.
In accordance with the various embodiments of the present
invention, the device may be made from a variety of materials such
as metal, composite, plastic or amorphous materials, which include,
but are not limited to, steel, stainless steel, cobalt chromium
plated steel, titanium, nickel titanium alloy (nitinol),
superelastic alloy, and polymethylmethacrylate (PMMA). The device
may also include other polymeric materials that are biocompatible
and provide mechanical strength, that include polymeric material
with ability to carry and delivery therapeutic agents, that include
bioabsorbable properties, as well as composite materials and
composite materials of titanium and polyetheretherketone
(PEEK.TM.), composite materials of polymers and minerals, composite
materials of polymers and glass fibers, composite materials of
metal, polymer, and minerals.
Within the scope of the present invention, each of the
aforementioned types of device may further be coated with proteins
from synthetic or animal source, or include collagen coated
structures, and radioactive or brachytherapy materials.
Furthermore, the construction of the supporting framework or device
may include radio-opaque markers or components that assist in their
location during and after placement in the bone or other region of
the musculo-skeletal systems.
Further, the reinforcement device may, in one embodiment, be osteo
incorporating, such that the reinforcement device may be integrated
into the bone.
In a further embodiment, there is provided a low weight to volume
device deployed in conjunction with other suitable materials to
form a composite structure in-situ. Examples of such suitable
materials may include, but are not limited to, bone cement, high
density polyethylene, Kapton.RTM., polyetheretherketone (PEEK.TM.),
and other engineering polymers.
Once deployed, the device may be electrically, thermally, or
mechanically passive or active at the deployed site within the
body. Thus, for example, where the device includes nitinol, the
shape of the device may be dynamically modified using thermal,
electrical or mechanical manipulation. For example, the nitinol
device may be expanded or contracted once deployed, to move the
bone or other region of the musculo-skeletal system or area of the
anatomy by using one or more of thermal, electrical or mechanical
approaches.
It is contemplated that the inventive implantable device, tools and
methods may be used in many locations within the body. Where the
proximal end of a device in the anatomical context is the end
closest to the body midline and the distal end in the anatomical
context is the end further from the body midline, for example, on
the humerus, at the head of the humerus (located proximal, or
nearest the midline of the body) or at the lateral or medial
epicondyle (located distal, or furthest away from the midline); on
the radius, at the head of the radius (proximal) or the radial
styloid process (distal); on the ulna, at the head of the ulna
(proximal) or the ulnar styloid process (distal); for the femur, at
the greater trochanter (proximal) or the lateral epicondyle or
medial epicondyle (distal); for the tibia, at the medial condyle
(proximal) or the medial malleolus (distal); for the fibula, at the
neck of the fibula (proximal) or the lateral malleoulus (distal);
the ribs; the clavicle; the phalanges; the bones of the metacarpus;
the bones of the carpus; the bones of themetatarsus; the bones of
the tarsus; the sternum and other bones, the device may be adapted
and configured with adequate internal dimension to accommodate
mechanical fixation of the target bone and to fit within the
anatomical constraints. As will be appreciated by those skilled in
the art, access locations other than the ones described herein may
also be suitable depending upon the location and nature of the
fracture and the repair to be achieved. Additionally, the devices
taught herein are not limited to use on the long bones listed
above, but can also be used in other areas of the body as well,
without departing from the scope of the invention. It is within the
scope of the invention to adapt the device for use in flat bones as
well as long bones.
While exemplary embodiments of the present invention have been
shown and described herein, it will be obvious to those skilled in
the art that such embodiments are provided by way of example only.
Numerous variations, changes, and substitutions will now occur to
those skilled in the art without departing from the invention. It
should be understood that various alternatives to the embodiments
of the invention described herein may be employed in practicing the
invention.
* * * * *
References